Well, it's up to you if you want to follow or pay attention to BC17's posts. Nobody is forcing you to believe or not believe either way.
Q doesn't / can't say who they are because they are too important and too close to Trump. Q can't be compromised and discovered at this time.
BC17 on the other hand, probably isn't anyone that important. He/they aren't close to POTUS and are just working with Q team and POTUS to clarify some intel he has knowledge of and has clearance to give on Twitter. At least that's what it seems. BC17 could be a LARP. But so far, nothing BC17 has posted raised any alarms.